Totally lost on this one.

I have a date values in Col I that are fed in from another sheet. These
dates may be typed in by a user in any format, but the critical info the year
and the month.

I have a series of months and years listed in Col A with corresponding info
in Col B that is only pertinent to that info in Col B. (Col B is the average
monthly outdoor temperature).

In another Column (let's call it M), I want to "index/lookup" the month and
year in Col I, match it with the month and year in Col A, and return the
value in Col B.

Any ideas?